Epilepsy Focus Mapping

What is Epilepsy Focus Mapping?

Epilepsy focus mapping, sometimes called brain mapping, is a surgical procedure in which surgeons place subdural grids directly on the brain to “map” the precise location of the source of the seizure as well as functional areas that control speech and movement. Once the focus of the seizure is identified, it can be removed during a procedure called focal cortical resection.

What to Expect Before Epilepsy Focus Mapping

Children are given a general anesthesia prior to the surgery. To prepare for the surgery, part of your child’s hair will be shaved.

What Happens During Epilepsy Focus Mapping?

An incision will be made and a craniotomy will be performed (removal of a piece of the skull that will be replaced at the end of the surgery). A subdural grid, which is a thin plastic strip with a series of electrodes embedded in it, is placed directly on the brain. Once the subdural grid is in place, the skull is closed. The cables from the grids will protrude from child's skull so they can be attached to a portable video EEG.

Your child will be in the Intensive Care Unit (ICU) overnight or until he or she is medically stable enough to go to the Epilepsy Monitoring Unit (EMU). While still in the ICU, your child will be observed continuously and blood pressure, pulse and respiration will be checked frequently.

What to Expect After Epilepsy Focus Mapping

Your child will then be moved to the Epilepsy Monitoring Unit, where his or her brain activity is monitored 24 hours a day. The epileptologist can then begin the brain mapping procedure. In epilepsy focus mapping, electrical currents stimulate portions of the brain via the subdural grids. The epilepsy doctor will monitor the child's movements and language to "map" the location of these important functional areas of the brain. The epilepsy surgeon then knows to avoid these areas during surgery.

The length of the epilepsy focus mapping process depends on how much brain tissue is targeted for surgery.

Epilepsy Focus Mapping Results

Once the epileptologist has enough information about the child's motor and language function from epilepsy focus mapping, the second part of this procedure, focal cortical resection, will be scheduled.

Potential Complications of Epilepsy Focus Mapping in Children

Every surgical procedure has associated risks, including infection, bleeding, and accumulation of water in the brain, called cerebral edema. The main risk associated with epilepsy focus mapping in children is that a seizure may be triggered. If a seizure occurs, the epilepsy doctor will stop the electrical stimulation until the child has fully recovered.

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